Binding of a monoclonal antibody and its Fab fragment to supported phospholipid monolayers measured by total internal reflection fluorescence microscopy.
The association of an anti-dinitrophenyl monoclonal antibody and its Fab fragment with supported phospholipid monolayers composed of a mixture of dipalmitoylphosphatidylcholine and dinitrophenyl-conjugated dipalmitoylphosphatidylethanolamine has been characterized with total internal reflection fluorescence microscopy. The surface densities of bound antibodies were measured as a function of the antibody and Fab solution concentrations, and as a function of the solution concentration of dinitrophenylglycine. The apparent association constant of Fab fragments with surface-associated haptens was approximately 10-fold lower than the association constant for haptens in solution, and the apparent surface association constant for intact antibodies was only approximately 10-fold higher than the constant for Fab fragments. Data analysis with simple theoretical models indicated that, at most antibody surface densities, 50-90% of membrane-associated intact antibodies were attached to the surface by two antigen binding sites.
Pisarchick
M L
ML
Department of Chemistry, University of North Carolina, Chapel Hill 27599-3290.
Thompson
N L
NL
D000911:Antibodies, Monoclonal / Q000378:metabolism*; D001665:Binding Sites; D055592:Biophysical Phenomena; D001703:Biophysics; D006241:Haptens; D007140:Immunoglobulin Fab Fragments / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D010743:Phospholipids / Q000378:metabolism*; D011485:Protein Binding; D012996:Solutions; D013499:Surface Properties
D000911:Antibodies, Monoclonal; D006241:Haptens; D007140:Immunoglobulin Fab Fragments; D010743:Phospholipids; D012996:Solutions